package org.rency.common.utils.security;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.apache.commons.codec.digest.DigestUtils;
import org.rency.common.utils.exception.CoreException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
  
public class MD5Utils {
	private static final Logger logger = LoggerFactory.getLogger(MD5Utils.class);
    /** 
     * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,apache校验下载的文件的正确性用的就是默认的这个组合 
     */  
    protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6',  
            '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };  
  
    protected static MessageDigest messagedigest = null;
      
    /** 
     * 生成字符串的md5校验值 
     *  
     * @param s 
     * @return 
     */  
    public static String MD5(String data) {  
        return DigestUtils.md5Hex(data);
    }  
      
    /** 
     * 判断字符串的md5校验码是否与一个已知的md5码相匹配 
     *  
     * @param password 要校验的字符串 
     * @param md5PwdStr 已知的md5校验码 
     * @return 
     */  
    public static boolean checkPassword(String password, String md5PwdStr) {  
        String s = MD5(password);  
        return s.equals(md5PwdStr);  
    }  
      
    /** 
     * 生成文件的md5校验值 
     *  
     * @param file 
     * @return 
     * @throws IOException 
     */  
    public static String getFileMD5String(File file) throws IOException {
    	try {  
            messagedigest = MessageDigest.getInstance("MD5");  
        } catch (NoSuchAlgorithmException nsaex) {  
        	logger.error(MD5Utils.class.getName()+ "初始化失败，MessageDigest不支持MD5Util。");  
            nsaex.printStackTrace();  
        } 
        InputStream fis;  
        fis = new FileInputStream(file);  
        byte[] buffer = new byte[1024];  
        int numRead = 0;  
        while ((numRead = fis.read(buffer)) > 0) {  
            messagedigest.update(buffer, 0, numRead);  
        }  
        fis.close();  
        return bufferToHex(messagedigest.digest()).toUpperCase();  
    }  
  
    /**
     * byte[]转换为字符串
     * @param bytes
     * @return
     */
    public static String bufferToHex(byte bytes[]) {  
        return bufferToHex(bytes, 0, bytes.length);  
    }  
  
    private static String bufferToHex(byte bytes[], int m, int n) {  
        StringBuffer stringbuffer = new StringBuffer(2 * n);  
        int k = m + n;  
        for (int l = m; l < k; l++) {  
            appendHexPair(bytes[l], stringbuffer);  
        }  
        return stringbuffer.toString();  
    }  
  
    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {  
        char c0 = hexDigits[(bt & 0xf0) >> 4];// 取字节中高 4 位的数字转换, >>> 为逻辑右移，将符号位一起右移,此处未发现两种符号有何不同   
        char c1 = hexDigits[bt & 0xf];// 取字节中低 4 位的数字转换   
        stringbuffer.append(c0);  
        stringbuffer.append(c1);  
    }  
    
    public static String bytesToHexString(byte[] src) {
      StringBuffer sb = new StringBuffer();
      if (src == null || src.length == 0) {
          return null;
      }
      for (int i = 0; i < src.length; i++) {
          String hex = Integer.toHexString(src[i] & 0xFF);
          if (hex.length() == 1) {
              hex = '0' + hex;
          }
          sb.append(hex.toUpperCase());
      }
      return sb.toString();
  }
    
    public static byte[] hexStringToBytes(String hexString) {
     if (hexString == null || hexString.length() < 1) {
         return null;
     }
     byte[] result = new byte[hexString.length() / 2];
     for (int i = 0; i < hexString.length() / 2; i++) {
         int high = Integer.parseInt(hexString.substring(i * 2, i * 2 + 1), 16);
         int low = Integer.parseInt(hexString.substring(i * 2 + 1, i * 2 + 2), 16);
         result[i] = (byte) (high * 16 + low);
     }
     return result;
 }
    
	public static void main(String[] args) throws CoreException {
		System.out.println("MD5="+MD5("rency"));
	}
}  